Here is a design with hinges

Duncan Fitzsimmons, a keen mountain biker, came up with the idea of a foldable road bike wheel.  The idea came when he tried to find a decent folder after moving to
London.   “The aim is to try to get a really high end city bike or courier bike that can fold up into a package like a golf bag, which could go into an overhead rack on a train or go into a plane locker.”  What do you think about this?  We like it — we just hope it locks.  This gives new meaning to the word “taco-ed tire.”

See the story here.